STORY: Exxon agreed on Wednesday (October 11) to buy U.S. rival Pioneer in a nearly $60 billion deal, making the supermajor a giant in the U.S. shale oil industry. It’s Exxon’s biggest deal since its $81 billion purchase of Mobil Oil in 1998.The companies said on Wednesday they had sealed an all-stock deal valuing Pioneer at $253 a share.Pioneer has been one of the most successful oil companies to emerge from the shale revolution, which turned the U.S. from a major oil importer into the world's largest producer in little more than a decade.This deal will leave four of the largest U.S. oil companies in control of much of the highly valued Permian Basin shale field. According to analysts, Pioneer is the Permian's largest operator, placing Exxon in the most dominant position. In the last two years, Exxon has pulled itself out of a period marked by deep losses and huge debts.It slashed costs, sold dozens of assets and benefited from high energy prices spurred by Russia's invasion of Ukraine.The oil giant's share price has recovered strongly since its early 2020 tumble to about $30 when oil and gas prices collapsed. Exxon shares recently hit an all-time high of $120 per share.